1. Field of the Invention
This invention relates generally to catheter guide wires for in vivo use, and more particularly to a guide wire for use in controlling the angular attitude of the distal tip of a catheter adapted to pass over the guide wire.
2. Description of the Related Art
Guide wires have been used for controlling the insertion of catheters in a vascular system, or other anatomical passageways, such as for purposes of angioplasty or for insertion of angioscopes or microsensor catheters. An interventional cardiologist may form a bend at the tip of the guidewire to assist in negotiation of branches in the vascular system, and the catheter is either carried along with the guide wire as it traverses the desired path in the vascular system, or the catheter is passed over the length of the guide wire once the guide wire has been placed in the proper position. In a catheter incorporating an angioscope for viewing the internal condition of a vascular system, in which the catheter carries fiber optic bundles for both illuminating the area to be viewed and for transmitting an image back to the proximal end of the catheter for viewing, the viewing direction or attitude of the distal end of the catheter may require some control by the operator for adequate examination of the area of interest.
It has been known to provide an endoscope catheter with a plurality of inflatable balloons, spaced at intervals near the distal end of the endoscope, which are alternatively inflatable to control the direction of the tip of the endoscope. Such a system is described in U.S. Pat. No. 4,040,413. A cable pulley arrangement has also been provided for varying the degree of bending of a catheter carrying fiber optics for illumination and viewing of an area at the distal end of the catheter. The cables are attached at the appropriate points about a sheath which is disposed circumferentially around the optical fibers and the viewing bundle. Such a catheter may also include a laser optical fiber. Control of the attitude of the catheter may be changed by pulling the proximal end on one or more of the cables to cause the catheter tip to tilt or move transversely for viewing and laser irradiation of the site of interest. Such a system is described in WO83/0183. Directional control of internal imaging apparatus within a catheter may also be provided by rotation of an optical element facing at an angle within the catheter, and tilting of the angle of an element, such as a mirror, by means of cables, as is discussed in U.S. Pat. No. 4,445,892.
While many of these systems of catheter attitude control have limited ability to provide the appropriate angular orientation, they have a number of limitations in their ability to provide a wide variety of viewing angles with a mechanically simple and reliable mechanism. Therefore, it would be desirable to provide a system for varying the attitude of the distal tip of a catheter, which has a minimum of complexity embodied within the catheter in order to facilitate the construction of smaller and less obstrusive catheters. The catheter tip attitude controlling guide wire of the present invention fulfills this need.